Interaction of Tritium with Elodea canadensis and Lemna minor.

Tritium is the least toxic radionuclide. The main contribution into the total tritium content in ecosystems is made by technogenic tritium, which is due to the operation of nuclear fuel cycle enterprises. The tritium content in the ecosystem of the River Yenisei is connected with its background values as well as with tritium entering the water ecosystem as a result of the operation of the Mining and Chemical Combine, MCC Rosatom.

Water properties from first principles: simulations by a general-purpose quantum mechanical polarizable force field.

We have recently introduced a quantum mechanical polarizable force field (QMPFF) fitted solely to high-level quantum mechanical data for simulations of biomolecular systems. Here, we present an improved form of the force field, QMPFF2, and apply it to simulations of liquid water. The results of the simulations show excellent agreement with a variety of experimental thermodynamic and structural data, as good or better than that provided by specialized water potentials.

A quantum mechanical polarizable force field for biomolecular interactions.

We introduce a quantum mechanical polarizable force field (QMPFF) fitted solely to QM data at the MP2/aTZ(-hp) level. Atomic charge density is modeled by point-charge nuclei and floating exponentially shaped electron clouds. The functional form of interaction energy parallels quantum mechanics by including electrostatic, exchange, induction, and dispersion terms.

PLASS: protein-ligand affinity statistical score--a knowledge-based force-field model of interaction derived from the PDB.

We have developed PLASS (Protein-Ligand Affinity Statistical Score), a pair-wise potential of mean-force for rapid estimation of the binding affinity of a ligand molecule to a protein active site. This scoring function is derived from the frequency of occurrence of atom-type pairs in crystallographic complexes taken from the Protein Data Bank (PDB). Statistical distributions are converted into distance-dependent contributions to the Gibbs free interaction energy for 10 atomic types using the Boltzmann hypothesis, with only one adjustable parameter.

[Chief types of placental trophism].

An attempt is made to represent a theory on two types of placental throphism. The first type--nutrition is mainly performed at the expense of maternal proteins, which in the placental chorion undergo proteolysis with formation of polypeptides and amino acids; embryospecific proteins are formed in the liver of the embryo. This type is characteristic for the animals with epithelio-chorionic acid and partly with desmo-chorionic placentas.

[Localization and volume of the derivatives of the prechordal plate of the cephalic gut in vertebrates].

In order to determine the localization and volume of the prechordal lamina derivatives the initial stages of histogenesis of the cephalic gut epithelium lining were studied in embryos of chickens and mammals (rabbits, rats, mice) in early terms of the formation of the fore-part of their digestive tube. It has been established that the derivatives characteristics of the prechordal lamina such as the cephalic end of the chordal, larval mesodermal somites, are formed by the real enterocelic means only from the entodermal epithelium of the Seessel's pouch walls which is the most cranial end of the cephalic gut. In other parts of the dorsal wall of the pharynx, the more of the oesophagus, the prechordal lamina derivatives fail to be determined.

[Human placental morphology as an index of features of maternal-fetal relationships].

Principle possibilities of the complex evaluation of the mother-fetus exchange were studied by means of morphological investigations of the human placenta in normality, in vesicular mole, late toxicoses, hemolytic disease of newborns and malformations of the fetus. The investigation of the ratio of the villi of different size, deposition of fibrinoid on their surface, the change of the amount of cytotrophoblastic elements, cells of Kaschenko-Hofbauer and the polymerity of the basic substance are of diagnostic value. The authors propose the basal lamina of the placenta to be included into the scheme of the examination of placenta.